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EJ25 block halves loosening sequence

General Engine Building Discussion

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Hey guys

Is there a specific loosening sequence for the EJ25 block halves? I’m running into some issues where after separating the block and refitting undersized bearings the clearances are all over the place. I did a dry assembly and that too reflected the same. The block was revisited because at high rpms the oil pressure fell too low, the original clearance were set at 2.7 thou across the board so was going to have them adjusted a bit tighter. The bearings that were removed had very slight wear with no evidence of taper or bore alignment issues. But now once assembled with and without bearings that’s not the case, all measurements were done using a dial bore gauge. So was trying to figure out if it’s because of the loosening method by the way I used the service manual method of loosening one half then the other.

Your input will be greatly appreciated.

The recommendation would be to loosen the block halves in the same order they are torqued however doing this in a different pattern shouldn't damage or distort the block halves. It's much more critical for clearances to make sure they are torqued up in the correct order. Are the dowels between the block halves still fitted?

Thanks much Andre and yes the two dowels are still fitted to the block, the biggest discrepancies are at 90 degrees to the parting lines. Using 2.520 as reference #1&5 as within spec #2&4 are +.0045 and #3 is +.002.

It sounds like you're going to need to have the parting faces of the block surfaced and then have the main bearing tunnel line honed to get that back on spec.

Yes thanks it sure looks so